A taper roller bearing has a feature of higher load capacity and higher rigidity than other rolling bearings of the same size.
FIG. 7 is an axially sectional view showing a taper roller bearing in the related art. FIG. 8 is a radially sectional view of the taper roller bearing in FIG. 7. As shown in FIG. 7 and FIG. 8, a taper roller bearing 100 includes an inner ring 101, an outer ring 102, a plurality of taper rollers 103 rotatably arranged between the inner and outer rings 101 and 102, and an annular cage 104 retaining the taper rollers 103 circumferentially at equal intervals (for example, see Patent Document 1).
The cage 104 includes a small diameter annular portion 105, a large diameter annular portion 106, and a plurality of pillar portions 107 which connect the two annular portions 105 and 106. In the cage 104, pockets 108 for receiving the taper rollers 103 are formed by the two annular portions 105 and 106 and adjacent ones of the pillar portions 107.
The cage 104 is positioned axially and radially by the taper rollers 103 respectively received in the pockets 108, while keeping the intervals between adjacent ones of the taper rollers 103.
To this end, the circumferential width of each pocket 108 is set to be smaller than the diameter of each taper roller 103 such that the taper roller 103 is received in the pocket 108 while sliding on the pillar portions 107, as shown in FIG. 8. The cage 104 is positioned radially when rolling surfaces 103a of the taper rollers 103 slide-contact the pillar portions 107, respectively.
In addition, inner side surfaces 108a of the pillar portions 107 on which the taper rollers 103 slide are formed into concave curved surfaces extending along the rolling surfaces 103a of the taper rollers 103, respectively, as shown in FIG. 8, such that the cage 104 is positioned accurately by the taper rollers 103.